.App {
  width: 300px;
  margin: 50px auto;
}

.nav {
  display: flex;
  height: 30px;
}

.nav a {
  flex: 1;
  display: flex;
  justify-content: center;
  align-items: center;
  background-color: #ddd;
  text-decoration: none;
  color: #333;
}

.nav .active {
  background-color: #f00;
  color: #fff;
}

.section {
  height: 200px;
  border: 1px solid #ddd;
}
